What causes keratosis pilaris (skin bumps)?

Why do I have keratosis pilaris?

Keratosis pilaris (KP) is a common, harmless skin condition that causes small, rough bumps—often described as “goose flesh”—on the skin. You might notice them on your upper arms, thighs, cheeks or buttocks. While KP is not dangerous, it can be persistent and cosmetically bothersome. Here’s what you need to know about what causes keratosis pilaris and why you may have developed those tiny skin bumps.

What is happening in your skin?

1. Keratin buildup

   • Keratin is a protein that helps protect skin from infections and other harmful things.
   • In KP, keratin accumulates around hair follicles, forming small plugs.
   • These plugs block the opening of the follicle, resulting in rough, pinpoint bumps.

2. Follicle “plugging”

   • Each bump often represents a slightly raised hair follicle filled with keratin.
   • The trapped keratin can leave dead skin cells sitting on the surface rather than shedding normally.

Main causes and risk factors

While the exact trigger isn’t fully understood, research and clinical experience point to a combination of factors:

• Genetics

  • KP often runs in families, suggesting a strong inherited component.
  • If one or both of your parents have the condition, your chances increase.

• Dry skin

  • Lack of moisture can worsen keratin buildup and roughness.
  • Flare-ups are more common in winter or in dry climates.

• Atopic conditions

  • People with eczema (atopic dermatitis), hay fever or asthma may be more prone to KP.
  • The same skin sensitivity that causes eczema can lead to follicular plugging.

• Age

  • KP often appears in childhood or adolescence, peaks in teenage years, then may improve in adulthood.
  • Some adults continue to have bumps into middle age and beyond.

• Obesity

  • Extra weight can increase friction and stress on skin, potentially exacerbating bumps.

• Hormonal changes

  • Fluctuating hormones—especially during puberty or pregnancy—can make KP more noticeable.

Why KP isn’t contagious or dangerous

• Keratosis pilaris is not an infection.
• You cannot spread it by touching or sharing personal items.
• It does not lead to cancer or serious skin disease.
• While the bumps can be itchy or red, they rarely hurt or become infected unless you pick at them.

How to tell KP apart from other conditions

• Folliculitis

  • A bacterial infection of the hair follicle, often painful or pus-filled.
  • KP bumps are dry, not typically inflamed or weeping.

• Milia

  • Tiny, white cysts under the skin, usually on the face.
  • KP is rough and may have a reddish or brownish tint.

• Eczema

  • Red, itchy patches, often oozing or crusted.
  • KP is localized to follicles and feels like sandpaper.

If you’re ever unsure about a skin change—or if bumps become painful, blistered or hot to the touch—talk with a healthcare provider or consider doing a free, online symptom check, using the doctor approved Ubie Symptom Checker.

Managing dryness and preventing flare-ups

Because dry skin is a key contributor, simple lifestyle changes often help:

• Gentle cleansing

  • Use mild, fragrance-free cleansers.
  • Avoid hot water; opt for lukewarm showers.

• Regular moisturizing

  • Apply a thick, cream-based moisturizer within minutes of bathing.
  • Look for products containing:
    • Urea (5–10%) to soften and dissolve keratin
    • Lactic acid (5–12%) to gently exfoliate
    • Glycerin or hyaluronic acid for hydration

• Humidifier use

  • Adding moisture to indoor air can reduce skin dryness, especially in winter.

• Avoid harsh scrubs

  • Over-exfoliating or rough scrubbing can irritate skin and worsen KP.
  • Instead, use a soft washcloth or a gentle chemical exfoliant.

When to seek medical advice

Most cases of keratosis pilaris don’t require medical treatment beyond self-care. However, see a doctor if:

• Bumps are extremely itchy, bleeding or showing signs of infection
• You’re unsure whether it’s keratosis pilaris or another skin condition
• Over-the-counter treatments aren’t helping after several months
• You feel anxious or self-conscious and want prescription options

Professional treatments

A dermatologist can offer stronger therapies, including:

• Topical retinoids (e.g., tretinoin) to speed skin cell turnover
• Stronger keratolytics (higher-strength lactic acid or salicylic acid)
• Laser therapy for redness or dark spots
• Prescription moisturizers combining urea, lactic acid and other agents

These approaches can improve the look and feel of your skin, though ongoing care is usually needed to keep bumps at bay.

Key takeaways

• Keratosis pilaris is caused by keratin plugging hair follicles, leading to rough, tiny bumps.
• Genetics, dry skin and atopic tendencies are major risk factors.
• It’s harmless, non-contagious and often improves with age.
• Gentle cleansing, regular moisturizing and gentle exfoliation are first-line steps.
• If you’re uncertain about your diagnosis or symptoms worsen, speak with a healthcare provider.

If you ever experience severe itching, pain, signs of infection or are worried about your skin, be sure to speak to a doctor. Serious or life-threatening conditions may require immediate medical attention.